PROJECT SUMMARY/ABSTRACT By the time children enter school, there is already tremendous variability in the size of their vocabulary. These early differences predict important long-term outcomes like academic success. An emerging body of research indicates that children?s vocabulary size is influenced by the quantity and quality of language they hear at home. While current initiatives seek to increase the amount of speech directed to children, it is equally important to improve the quality of that speech. When children hear a novel word, they are frequently surrounded by many potential referents. Unless they can identify the correct referents for novel words, they will not benefit from increased language exposure. The research proposed in this application will examine how 3-year-olds integrate multiple types of cues to identify the correct referents of novel words. Specific Aim 1 will investigate whether cooperating cues have an additive effect on word learning. In Study 1, children will see a video of an adult labeling a novel object in the presence of another potential referent. Children will be able to use either the speaker?s gaze, the presence of a familiar object with a known name, or both cues to determine the correct referent of the novel word. Children?s fixations to the target object will be compared in all three conditions to determine whether the presence of both cues improves their ability to identify the correct referent. Subsequent trials without any cues will test children?s ability to learn and retain the novel object?s names. Specific Aim 2 will determine whether children can combine ambiguous cues to learn new words. In Study 2, novel objects will be labeled in the presence of three other potential referents. Unlike in Study 1, each word- learning cue will be insufficient on its own ? eliminating some, but not all potential referents. Children will only be able to determine the correct referent of the novel word by using both the speaker?s gaze and the presence of familiar objects with known names. Children?s fixations to the target object will be compared to chance to determine whether they succeed in combining cues to identify the correct referent. Subsequent trials without any cues will test children?s ability to learn and retain the novel object?s names. Specific Aim 3 will examine individual differences in children?s attention to word-learning cues. In Studies 1 & 2, children?s fixations to the speaker?s face vs. the familiar objects with known names will be compared to determine: 1) the degree to which individual children attend to both cues equally or preferentially attend to one cue and 2) whether individual differences in the distribution of children?s attention predict their success in word learning. Results from these studies will significantly advance our understanding of how children combine multiple cues to identify the referents of novel words. These findings will provide insights into how parents can improve the quality of their speech to help children identify the referents of novel words and will contribute to current initiatives that seek to improve children?s language development.